Gas fired heating appliance with safety release door mechanism

ABSTRACT

A gas fired heating appliance comprising a chassis, a firebox having an interior cavity having a gas burner and an opening communicating the interior of the firebox with an environment external to the appliance, a door for enclosing the opening, and at least one track member. The track member has a retracted position and an elongated extended position, and also has a first end secured to the chassis or the firebox and a second end engaging the door. When in its retracted position the track member positions the door to enclose and seal the opening. When in its extended position the track member retains the door in a position outwardly off-set from the firebox adjacent the opening.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Canadian Application filed in the Canadian Patent Office on Dec. 8, 2014. The disclosure of the application is hereby incorporated by reference in its entirety herein.

TECHNICAL FIELD

This invention relates generally to gas fired heating appliances, and in particular to such an appliance incorporating a safety release door mechanism.

BACKGROUND

Due to their convenience, energy efficiency, and reduced hydrocarbon emissions, natural gas and propane burning fireplaces, stoves and other similar heating appliances have, to a large extent, displaced wood burning appliances in many geographic locations. Over the years, gas and propane burning appliances have become common in both residential and commercial settings. A significant percentage of gas burning appliances that are installed are of the direct vent type, wherein the firebox is sealed from the room within which it is installed and combustion air is drawn from an outside environment into the firebox.

Direct vent appliances offer a number of advantages, the most significant of which is an increase in overall efficiency. However, a sealed firebox can also present particular dangers that should be recognized and accounted for in the appliance design. One such danger involves a delayed ignition that can occur when an individual attempts to light the appliance after natural gas or propane has accumulated within the firebox. Igniting a significant volume of accumulated gas can effectively cause a small explosion. In certain instances these explosions can result in the front door of the appliance being blown into the room within which the appliance is installed. Since the doors of the appliances are often manufactured largely from glass, the glass can break, with fragments being expelled outwardly and potentially damaging individuals and property. Even where the door glass does not shatter upon being exposed to the pressure of the gas ignition, the door can be forced into the room, potentially damaging the door, breaking the glass, damaging property in the immediate vicinity of the fireplace and/or causing personal injury.

To help avoid the possibility of appliance doors shattering and/or being blown into a living space under delayed ignition situations, others have suggested installing relief dampers within the firebox that can relieve the over-pressure in the event of delayed ignition. The use of relief dampers can result in varying degrees of effectiveness. If the internal resistance of the damper is too great, the dampers will not open and will not provide an effective means to release internal pressure. On the other hand, should the resistance of the dampers be too low, the dampers may tend to open when internal pressures within the firebox are well below the pressures that may cause safety concerns, resulting in a loss of heating efficiency and combustion performance Further, the mechanical nature of current relief dampers is such that they warp or become deformed due to exposure to high temperatures, can become corroded, or over time they can react sluggishly with their ability to properly function slowly diminished.

SUMMARY

One aspect of the invention therefore provides a gas fired heating appliance comprising a chassis, a firebox having an interior cavity having a gas burner, said firebox including an opening communicating the interior of the firebox with an environment external to the appliance; a door for enclosing the opening; at least one track member, said track member having a retracted position and an elongated extended position, said track member having a first end secured to said chassis or said firebox and a second end engaging said door, when in said retracted position said track member positioning said door to enclose and seal said opening, when in said extended position said track member retaining said door in a position outwardly off-set from the firebox adjacent said opening.

Another aspect of the invention provides a gas fired heating appliance comprising a chassis, a firebox having an open front enclosed by a door, the door including a viewing window and a frame; a gas burner; and one or more track members, said track members having a retracted position and an elongated extended position, said track members having first ends secured to said chassis or said firebox and second ends engaging said frame of said door, when in said retracted position said track members positioning said door so as to enclose said front of said firebox, when in said extended position said track members retaining said door in a position outwardly off-set from said firebox, said track members movable from said retracted position toward said extended position through the application of firebox pressure, elevated beyond a pre-determined value, to said door.

Another aspect of the invention provides a gas fired heating appliance comprising a chassis, a firebox having a pressure release openings therein; a door associated with said pressure release opening, said door having a closed position wherein it effectively seals said pressure release opening to prevent or limit the flow of gases through said pressure release opening, said door having a displaced position wherein gases from within said firebox are allowed to flow through said pressure release opening; one or more track members associated with said door, said track members having a retracted position and an extended position, said track members having a first end secured to said chassis or said firebox and a second end engaging said door, when in said retracted position said track members positioning said door such that said door encloses said pressure release opening, when in said extended position said track members retaining said door in a position outwardly off-set from said firebox, said track members comprising two or more telescoping members that telescope when said track members are moved between said retracted and said elongated positions; and biasing means to bias said track members to said retracted position.

Further aspects of the invention will become apparent from the following description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show exemplary embodiments of the present invention in which:

FIG. 1 is a side perspective view of a gas fireplace exemplifying an embodiment invention.

FIG. 2 is a side perspective view similar to FIG. 1 wherein the exterior side and top panels of the fireplace have been removed.

FIG. 3 is view similar to FIG. 2 wherein the fireplace door has been displaced outwardly from the front of the fireplace.

FIG. 4 is an enlarged detail view of the attachment of the fireplace door to track members.

FIG. 5 is a view similar to FIG. 3 wherein the fireplace door has been removed from the track members and wherein the door does not include a decorative screen attached thereto.

FIG. 6 is an outer side view of one of the track members shown in FIG. 3 in a retracted position.

FIG. 7 is an outer side view of one of the track members shown in FIG. 3 in an extended position.

FIG. 8 is an inner side view of one of the track members shown in FIG. 3 in an extended position.

FIG. 9 is a view similar to FIG. 3 wherein the fireplace door is in the process of being returned to its position sealed against the front of the firebox and includes an alternate form of decorative screen.

FIG. 10 is an alternate embodiment of the invention to that shown in FIG. 1.

FIG. 10A is an enlarged detail view of portion A of FIG. 10.

FIG. 11 is a view similar to FIG. 10 wherein the fireplace door has been displaced outwardly from the front of the fireplace.

FIG. 12 is an alternate embodiment of the invention to that shown in FIGS. 1 and 10.

FIG. 12A is an enlarged detail view of portion A of FIG. 12.

FIG. 13 is an upper side perspective view of the fireplace shown in FIG. 12.

FIG. 14 is an alternate embodiment of the invention to that shown in FIGS. 1, 10 and 12.

FIG. 14A in an enlarged detail view of portion A of FIG. 14.

FIG. 15 is a view similar to FIG. 14 wherein the fireplace door has been displaced outwardly from the front of the fireplace.

FIG. 15A is an enlarged detail view of portion A of FIG. 15.

DETAILED DESCRIPTION

The present invention may be embodied in a number of different forms. The specification and drawings that follow describe and disclose some of the specific forms of the invention.

The attached drawings depict an exemplary embodiment of the invention wherein the gas heating appliance is shown as a gas fireplace. It will, however, be appreciated from a thorough understanding of the invention that although a gas fireplace has been shown, various other heating appliances are embodied within the invention. For example, the appliance could equally be a gas wall heater or a free-standing gas stove.

In FIGS. 1 through 5 there is shown a relatively standard gas fireplace that generally comprises an outer housing or chassis 1, a removable door 2 (with or without a decorative screen 11), a firebox 3 having a generally open front that is enclosed by door 2, a gas burner 4 and an intake/exhaust port 5. In this instance the fireplace is a direct-vent fireplace where the intake and exhaust are concentric ducts. Door 2 may be in any one of a wide variety of forms. In the embodiment shown, the door is comprised of a glass viewing window 6 surrounded and held by a frame 7. Here, the door is generally rectangular having two side portions 8, a top portion 9 and a bottom portion 10. The door encloses the front of the firebox to present a sealed fire chamber so as to limit the possibility of the intrusion of flammable or noxious gases into the room within which the fireplace is situated.

Where the fireplace includes a decorative screen 11, the screen would typically include a number of rearwardly extending arms 12 that hook into mounts or slots 26 on door frame 7 so that the screen may be effectively hung from the door.

With reference to FIG. 2, the appliance may include one or more latches 13 that releasably engage door 2. When engaged with the door, the latches releasably secure the door about the open front of the firebox. That is, the latches serve the function of holding the door tightly in place, maintaining the seal between the firebox and the door, and permitting the door to be removed for servicing the gas burner and cleaning the interior of the firebox.

In accordance with an embodiment of the invention there is further provided one or more track members 14 comprised of two or more telescoping members. Track members 14 may be telescoping and/or pneumatic cylinders and/or hydraulic cylinders. In the particular embodiment shown in FIGS. 2 through 5 the track members comprise telescoping inner, middle and outer rails (15, 25 and 16 respectively). While three nested or telescoping rails have been shown, other combinations and numbers of rail components could also be used. Track members 14 have first ends 17 that are secured to the chassis, the firebox or other fixed or structural portion of the fireplace, and second ends 18 that engage door 2. The track members have a retracted position (where the rails substantially overlap one another) and an elongated extended position (where the degree of overlapping of the rails is less than in the case of the retracted position). With the first ends 17 of track members 14 secured to the chassis or the firebox, and with second ends 18 of the track members secured to door 2, when the track members are in their retracted position the door will be positioned to enclose front of the firebox. Similarly, when the track members are in their extended position the door will be held outwardly off-set from the front of the firebox, generally parallel to the front of the appliance and in a generally vertical plane (see FIG. 3). It will further be noted that where door frame 7 has mounted thereto a decorative feature (for example, a screen) the displacement of the door to an outwardly off-set position will cause a corresponding displacement of the decorative feature. Preferably, track members 14 include one or more stoppers 19 that prevent separation of the component rails when the track members are moved to their extended position. It will be appreciated by one of skill in the art that a very wide variety of different stoppers could be utilized to perform the intended function.

In FIGS. 2 through 5 the depicted fireplace is shown as including a pair of track members 14, one mounted on each side of the fireplace and engaging opposite sides of door frame 7. Other configurations of track members could also be incorporated within the design of the appliance. For example, there could be multiple track members running along each respective side of the fireplace, track members could be mounted on the top and bottom of the fireplace such that they engage the top and bottom portions of the door frame, or track members could be mounted on all four sides of the chassis or the firebox and engage all four sides of the door frame.

In a further embodiment, a single track member could be used to engage the door. In such cases it is expect that the track member and the frame of the door will need to be sufficiently rigid to enable the door to be effectively supported from a single point. In addition, the track member may be in the form of a series of wide, nested, plates that engage the door over a significant portion of a side or the top portion of the door frame.

With reference once again to FIGS. 3 and 4, in one embodiment of the invention second ends 18 of track members 14 include hooks 20 that receive complimentary shaped pins 21 on frame 7. Hooks 20 are preferably oriented in an upward direction so that the pins on the door frame can be lowered into the hook bowls to effectively hang the door from the track members. Other ways to mount the door to the track members are possible (including other configurations and variations of hooks; pins and other releasable mounts; and screws, bolts and other fasteners, etc.) without significantly affecting the overall functionality of the invention. Through mounting the door to the ends of the track members in this fashion the door can easily be lifted from the track members and removed completely from the fireplace to allow unobstructed access to the interior of the firebox for service and/or cleaning.

Having in mind the above described structure, the operation of track members 14 and latches 13 will now be described in further detail with reference to a situation of delayed ignition. If for any reason there should be a delayed ignition of gas within the firebox when the appliance is fully assembled and the door held tightly in place, the increased pressure within the firebox will bear directly against door 2. If the pressure is low enough, it will be simply vented through the exhaust without any noticeable affect. However, where the pressure is significant (to the point where it could cause damage to the appliance or its surroundings) latches 13 will disengage, permitting door 2 to be pushed outwardly from the front of the appliance, thereby allowing for the dissipation of internal pressure from within the firebox. As the door is pushed outwardly, track members 14 will move from their retracted to their extended position, while at the same time holding the door firm and maintaining the door in a position that is generally parallel to the front of the appliance and generally vertical.

Track members 14 may include one or more biasing members 30, which may be one or more springs, hydraulic or pneumatic cylinders, and/or one or more friction inducers that retard the movement of the track members from their retracted to their extended position. Biasing members 30 will effectively help to “absorb” some of the pressure from the delayed ignition within the firebox, and will also help to reduce the likelihood of the door being blown outwardly at a velocity that could result in damage to the door and/or the track members. In one embodiment, springs, having one end secured to the outer rail 16 of the track member and their opposite end secured to either the inner rail 15, chassis 1, firebox 3 or the outer housing 1 of the fireplace, may be used. In an alternate embodiment, friction inducers (made from rubber or other friction inducing material) may be positioned between the inner and outer rails. Further, a friction inducing coating may be applied to portions (for example, see areas 27 in FIG. 7) of the rails. In yet a further embodiment the dimensional tolerances of the inner and outer rails may be such that there is sufficient inherent friction between the respective rails to help “control” the rate of movement of the track members to their extended position. To permit both a release of internal pressure from within the firebox, and to also help to prevent the door from being blown outwardly at an excessive rate, the biasing means can be designed to only retard the rate of extension of the rails once the seal between the door and the firebox has been broken and internal gases have been given an opportunity to escape.

In instances where biasing means 30 are utilized, their function could also extend to retaining the door in place within the front opening of the firebox. In such instances biasing means 30 may effectively remove the need for the use of latches 13. That is, the biasing means could be positioned (and their biasing force chosen) such that they draw door 2 into contact with the front of the fireplace to hold the door in position and to effectively seal the front of the firebox. In the case of an over-pressure situation within the firebox the biasing means would still permit the door to extend outwardly to relieve the excess internal pressure.

In embodiments where latches 13 are utilized, to “release” the door from the firebox, and to allow over-pressure within the firebox to dissipate without damaging the appliance, it will be understood that latches 13 must be designed to disengage (or at least partially release) the door upon the pressure within the firebox exceeding a predetermined value. While a variety of mechanisms could accomplish that goal, it is expected that in most instances latches 13 will frictionally engage door 2 so that when the pressure within the firebox exceeds the frictional force holding the door in place, the door will be allowed to be moved outwardly from the front of the firebox. To that end latches 13 may include springs 22 so that the release of the latch requires a force exceeding that applied by the spring. In such instances the spring constant of the springs can be chosen to permit the door to move outwardly via track members 14 when internal pressure exceeds a pre-determined value (ie it exceeds the force applied by the springs). As the door moves outwardly following a delayed ignition, it will be held parallel to the front of the fireplace by track members 14 as described above. Once the seal between the door and the fireplace has been broken, excess pressure will vent into the surrounding room until the internal fireplace pressure is reduced to the point where the springs of the latches draw the door back into contact with the front of the fireplace. The door will then be returned to its original position and the potentially dangerous delayed ignition condition will have been safely dealt with.

FIGS. 10, 10A and 11 show an alternate embodiment of the invention. Here, track members 14 have been replaced with pneumatic or hydraulic cylinders 52. Cylinders 52 will largely function similar to track members 14 with the body 53 of the cylinders mounted to the side surface of the firebox or the chassis, and the end of the cylinder rod 54 fixed or otherwise secured to door 2. It is expected that in most instances the end of the rod will be releasably secured to the door to allow the door to be completely removed from the fireplace if desired. Pneumatic or hydraulic cylinders 52 are normally biased to its retracted position such that they cause the door to be drawn inwardly, thereby sealing the open front of the firebox. Since cylinders 52 will provide a positive force drawing the door into contact with the front of the fireplace, in most cases it is expected that there will be no need for the utilization of separate latches to retain the door in place. Cylinders 52 thus perform the dual function of securely holding the door in place and sealing the firebox, and providing a pressure release mechanism by which the door can be displaced outwardly from the front of the firebox to release built up internal pressure if such pressure were to exceed a predetermined level. Once the internal pressure has dissipated, cylinders 52 will draw the door back into contact with the fireplace and re-seal the firebox.

FIGS. 14, 14A, 15 and 15A show a different embodiment of the invention wherein track members 14 have been replaced by a single cylinder 55 mounted at the top of the fireplace. As in the case of cylinder 52, it is expected that cylinder 55 will be a hydraulic or pneumatic cylinder, however, it will be appreciated that a spring activated cylinder could also be utilized for either cylinder. In this case, cylinder 55 includes a cylinder body 56 and a cylinder rod 57. Body 56 will generally be mounted along the central portion of the upper surface of the fireplace and at an angle of approximately 90° to the fireplace door. Rod 57 may include a lateral support member 58 that extends outwardly from either side of rod 57 at 90° such that support member 58 is generally parallel to fireplace door 2. Support member 58 may then be releasably secured to the upper or top portion of fireplace door 2 to thereby effectively releasably secure the door to the fireplace.

The function of cylinder 55 will essentially be the same as that of cylinder 52, in that the cylinder will perform the dual function of retaining the fireplace door tightly against the front of the fireplace in order to maintain an airtight seal, while at the same time permitting the dissipation of internal pressure that exceeds a predetermined value. With the use of a single cylinder 55, lateral support member 58 assists in securely holding fireplace door 2 in place and maintaining it in a proper orientation and position vis à vis the front of the fireplace. Body 56 and/or rod 57 and/or support member 58 may include elements to prevent rotation of rod 57 such that the fireplace door is at all times maintained in a proper orientation that will allow the door to move outwardly and then be retracted back inwardly while remaining “square” and sealed with the front of the fireplace. It will also be appreciated that while not shown in the attached drawings, multiple cylinders 55 could be used if desired (and in particular for exceedingly heavy or wide doors). Further, in some instances cylinder or cylinders 55 may be positioned on the sides of the fireplace.

FIGS. 15 and 15A depict an embodiment of the invention shown in FIG. 14 wherein the fireplace door has been displaced outwardly on account of the build up of excessive firebox pressure, resulting in an extension of rod 57 from body 56 thereby presenting an opening in the front of the fireplace through which excess firebox pressure can dissipate. Of course, it will be appreciated that when servicing or cleaning of the firebox is necessary, an individual merely need to grasp the door and pull it outwardly with sufficient force to off-set that of cylinder 55. Once the door has been moved outwardly from the front of the fireplace, a cylinder lock (which could comprise a pin, snap ring, etc.) can be inserted about rod 57 in order to prevent it from being drawn back into body 56 so that the door may be removed from lateral support member 58 to provide full access to the interior of the firebox. Alternately, a mechanical lock or brace could be positioned on the surface of the fireplace such that it engages one or both of rod 57 and lateral support 58 to retain the rod in an extended position.

In still a further alternate embodiment of the invention the firebox includes a pressure release opening 50 through which gases from within the firebox can escape upon internal firebox pressure exceeding a predetermined level. The pressure release opening is a separate opening in the firebox, distinct from the open front, and may be located in the top, back, bottom or side surfaces. Multiple pressure release openings may be utilized. For illustration purposes, in FIGS. 12 and 13 pressure release opening 50 is located in the back surface of the firebox. In this embodiment, a door 51 is used to normally enclose pressure release opening 50 and to seal and prevent the escape of gases from within the firebox through the opening. Door 51 maybe secured to the firebox through the use of one or more track members 14 that are configured to function essentially the same as the track members secured to door 2. The track members will serve to position door 51 about pressure release opening 50, while permitting door 51 to be offset from the surface of the firebox upon the internal pressures within the firebox exceeding a predetermined level. Track members 14 may include one or more biasing means to both help retard the movement of the track members from their retracted to their extended positions, and to return door 51 to its position enclosing pressure release opening 50 upon the dissipation of the internal pressure within the firebox. As in the case of the embodiment described above, the biasing means could be any combination of one or more springs, hydraulic or pneumatic cylinders, belleville washers, etc. It will be appreciated by those of ordinary skill in the art that if desired, firebox 3 may include one or more pressure release openings 50 enclosed by doors 51 mounted on track members 14, as well as a primary door 2, also mounted on separate track members. Further, as shown in FIGS. 12 and 13, door 51 may alternately be secured to the firebox through the use of one or more hydraulic or pneumatic cylinders 52, with or without the use of separate latches.

It will thus be appreciated that the described structure provides a safety release door mechanism that helps to prevent damage to the appliance and the surroundings in the room within which the appliance is situated, and that helps to prevent personal injury in the case of delayed ignition within the firebox. In an over-pressure situation the door is allowed to move outwardly from the firebox in a controlled manner in order to dissipate the internal pressure, while at the same time preventing the door from being blown into the room and minimizing twisting or distorting (which can cause breakage of the glass). The structure further presents service personnel with a simplified manner of removing the appliance door. Where for service purposes it is necessary to access the interior of the firebox, where latches 13 are present they can be manually disengaged from door 2, at which point the door can be grasped and pulled outwardly from the front of the appliance. Track members 14 will thus support the weight of the door and hold it securely in position adjacent to the front of the fireplace. At that point the door can be lifted from hooks 21 on the ends of the track members and fully removed from the appliance, thereby exposing the entire front of the firebox. Replacing the door merely requires engaging pins 21 with hooks 20, sliding the door back into place in the front of the firebox and re-engaging the latches. If latches 13 are not utilized and the door is retained solely by track members 14 and biasing means 30, moving the door outwardly for servicing will require a disengagement of the biasing means from the latches or the application of a force that exceeds that applied by the biasing means.

It is to be understood that what has been described are the preferred embodiments of the invention. The scope of the claims should not be limited by the preferred embodiments set forth above, but should be given the broadest interpretation consistent with the description as a whole. 

What is claimed is:
 1. A gas fired heating appliance comprising: a chassis; a firebox having an interior cavity having a gas burner, said firebox including an opening communicating the interior of the firebox with an environment external to the appliance; a door for enclosing the opening; and at least one track member, said track member having a retracted position and an elongated extended position, said track member having a first end secured to said chassis or said firebox and a second end engaging said door, when in said retracted position said track member positioning said door to enclose and seal said opening, when in said extended position said track member retaining said door in a position outwardly off-set from the firebox adjacent said opening.
 2. The appliance as claimed in claim 1 including one or more latches that when engaged with said door releasably secure said door about the opening.
 3. The appliance as claimed in claim 1 wherein said door, when retained outwardly off-set from the firebox by said track member, is generally parallel to the adjacent face of the appliance.
 4. The appliance as claimed in claim 3 wherein said door includes a frame, said frame generally rectangular having two side portions, a top portion and a bottom portion, said appliance including two track members, with one track member engaging each side portion of said frame.
 5. The appliance as claimed in claim 3 wherein said door includes a frame, said frame generally rectangular having two side portions, a top portion and a bottom portion, said appliance including two track members, with one track member engaging each of the top and bottom portions of the frame.
 6. The appliance as claimed in claim 4 wherein said second ends of said track members include hooks that receive complimentary shaped pins on said frame, said pins releasably receivable within said hooks to effectively hang said door from said second ends of said track members.
 7. The appliance as claimed in claim 6 wherein said frame includes mounts for a decorative feature, displacement of said door to said outwardly off-set position causing a corresponding displacement of said decorative feature.
 8. The appliance as claimed in claim 7 wherein said decorative feature comprises a decorative door or screen.
 9. The appliance as claimed in claim 1 wherein said track member comprises telescoping inner and outer rails and a stopper preventing separation of said inner and outer rails when said track member is moved to said extended position.
 10. The appliance as claimed in claim 9 wherein said track member includes one or more friction inducers to retard movement of said track member to said extended position.
 11. The appliance as claimed in claim 10 wherein said friction inducers are one or more springs.
 12. The appliance as claimed in claim 2 wherein said one or more latches disengage said door upon the pressure within said firebox exceeding a predetermined value, thereby permitting said track members to move to said extended position such that said door no longer encloses said opening and permitting a dissipation of internal pressure.
 13. The appliance as claimed in claim 1 wherein said track member comprises a pneumatic or hydraulic cylinder.
 14. A gas fired heating appliance comprising: a chassis; a firebox having an open front enclosed by a door, the door including a viewing window and a frame; a gas burner; and one or more track members, said track members having a retracted position and an elongated extended position, said track members having first ends secured to said chassis or said firebox and second ends engaging said frame of said door, when in said retracted position said track members positioning said door so as to enclose said front of said firebox, when in said extended position said track members retaining said door in a position outwardly off-set from said firebox, said track members movable from said retracted position toward said extended position through the application of firebox pressure, elevated beyond a pre-determined value, to said door.
 15. The appliance as claimed in claim 14 further including one or more latches engageable with said frame to releasably secure said door about the front of the firebox.
 16. The appliance as claimed in claim 14 wherein said track members are pneumatic or hydraulic cylinders.
 17. The appliance as claimed in claim 14 wherein said track members include one or more friction inducers to retard movement of said track members to said extended position.
 18. The appliance as claimed in claim 17 wherein said one or more friction inducers are one or more springs.
 19. A gas fired heating appliance comprising: a chassis; a firebox having a pressure release openings therein; a door associated with said pressure release opening, said door having a closed position wherein it effectively seals said pressure release opening to prevent or limit the flow of gases through said pressure release opening, said door having a displaced position wherein gases from within said firebox are allowed to flow through said pressure release opening; one or more track members associated with said door, said track members having a retracted position and an extended position, said track members having a first end secured to said chassis or said firebox and a second end engaging said door, when in said retracted position said track members positioning said door such that said door encloses said pressure release opening, when in said extended position said track members retaining said door in a position outwardly off-set from said firebox, said track members comprising two or more telescoping members that telescope when said track members are moved between said retracted and said elongated positions; and biasing means to bias said track members to said retracted position.
 20. The appliance as claimed in claim 19 wherein said pressure release opening is positioned in the back, top, bottom or side surfaces of said firebox.
 21. The appliance as claimed in claim 19 wherein said door is generally rectangular and said appliance includes two track members, one track member engaging a first side of said rectangular door and the other track member engaging an opposite second side of said rectangular door.
 22. The appliance as claimed in claim 19 wherein said biasing means comprises one or more springs, hydraulic or pneumatic cylinders, or belleville washers.
 23. The appliance as claimed in claims 19 having a single track member engaging said door, said track member comprising a pneumatic or hydraulic cylinder having a cylinder body and a cylinder rod, said cylinder rod including a lateral support member extending outwardly from opposite sides of said rod at approximately 90 degrees, said cylinder body mounted to said firebox and said door mounted to said lateral support member.
 24. The appliance as claimed in claim 19 wherein said second ends of said track members include hooks that receive complimentary shaped pins on said door, said pins releasably receivable within said hooks to effectively hang said door from said second ends of said track members.
 25. The appliance as claimed in claim 24 wherein said door encloses an open front of said firebox and includes mounts for a decorative feature, displacement of said door to said outwardly off-set position causing a corresponding displacement of said decorative feature. 